Door for bomb and gas resisting shelters, buildings, and the like



June 13, 1944. P. BESCHERER DOOR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS, AND THE LIKE Filed May 21, 1942 8 Sheets-Sheet l finventor PALME R B ESCHERER June 13,

1944. P. BESCHERER DOOR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS, AND THE LIKE Filed May 21, 1942 8 Sheets-Sheet 2 Buncntor PALMER BESCHERER Gttorneg June 13, 1944. BESCHERER 2,350,981

DOOR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS, AND THE LIKE Filed May 21, 1942 8 Sheets-Sheet 3 :mventor PALMER BES-CHERER (Ittomeg June 13, 1944. P. BESCHERER DOOR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS, AND THE LIKE Filed May 21, 1942 8 Sheets-Sheet 4 m 5 .w. C a Q. B R E m mm m Om NM NM m v 7 mm NV 3 mm a a my Q June 13, 1944. BESCHERER 2,350,981

AND THE LIKE DOOR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS,

Filed May 21, 1942 8 Sheets-Sheet 5 mm mm vom Smwntor PALMER BESGH ERER mm mm Ottoman} June 13, 1944. BEscHERER 2,350,981 I UUUR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS, AND THE LIKE Filed May 21, 1942 8 Sheets-Sheet 6 Immntor PALMER BESCHERER June 13, 1944. P BEscHERER 2,350,981

DOOR FOR BOMB AND GAS RESIS'IING SHELTERS, BUILDINGS, AND THE LIKE Filed May 21, 1942 8 Sheets-Sheet '7 Snventor PALMER BESCHER ER (Ittorneg June 13, 1944. P. BESCHERER DOOR FOR BOMB AND GAS RESISTING SHELTERS, BUILDINGS, AND THE LIKE 8 Sheets-Sheet 8 Filed'May 21, 1942 3nnentor PALMER BESCHE R ER (Ittorneg I Patented June 13,

noon roa norm AND GAS RESISTING snnnrnas, nurmmos, AND 'rne mm Palmer Bescherer, York, Pa., as'siznor to York Safe and Look Company, York, Pa... a corporation of Delaware Application myv 21, 1942, Serial No. 443,890

a claims. (CI. 20-16) This invention relates to doors and more par-- ticularly to doors of the type adapted to provide closures for bomb and gas resisting shelters, buildings. and the like.

An object of the invention is to provide an improved door for bomb and gas resisting shelters and the like, in which means are provided for permitting free swinging movement of the door under ordinary conditions, said means being adapted, when a blast or other abnormal pressure is expected on the exterior of the structure to which the door is applied, to permit the door to swing through an erect safety without the blast tearing the door apart from the structure or otherwise damaging the door and without effecting movement of the door to the position a in which the door opening in the structure is opened so that gases or other matter from the blast can enter the interiorof the structure. ,7 Another object of the invention is to provide means for retarding the movement of I a door of f a bomb and gas resisting shelter, by which the door is permitted to swing through a limited arc when struck by a blast from a bomb or other explosive element.

Another object'of the invention is to provide improved means for swingingly mounting a door, in which theusual hinges are dispensed with.

Another object of the invention is to provide an improved means for sealing the openings'of bomb and gas resisting shelters and the like, so that the penetration of gases, etc. into the shelters is prevented, even when the doors are swung through a considerable arc.

With the foregoing and other objects and advantages in view, the invention consists in the preferred construction and arrangement of the several parts which will be hereinafter more fully described and claimed.

In the accompanying drawings:

Fig. 1 is a horizontal section of a door struc ture embodying the present invention;

Fig. 2 is a vertical transverse section taken on the line 22 of Fig. 1, looking at the outside of the door;

Fig. 3 is a vertical transverse section taken on the line 38 of Fig. 1, looking at the inside of the door;

Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 3, showing the brake off;

Fig. 5 is a view similar to Fig. 4, showing the brake on; f

Fig. 6 is a vertical transverse section taken on the line 66 of Fig. 1;

Fig. ,7 is a view similar to Fig. 1, ona smaller scale, showing the door in another position; and Fig. 8 is a section taken on the line 8-8 of Fig. 1.

During air raids in time of war itis the custom for the populace to take shelter, when possible, in specially designed buildings known as air raid shelters. In order to protect the occupantsof such buildings, by the present invention, it is proposed to'provide animproved type of door adapted to be so mounted in an entrance of the building that it will resist the blasts of bombs falling in close proximity to the shelter or building.

It has been found that exploding bombs dropped in Proximity to air raid shelters having steel doors of the usual type, ripped the doors free of their fastenings and otherwise damaged the doors. The damages to the doors resulted from the fact that the doors were ilrmly locked in closed position in the usual manner with steel fasteners and-bolts and had no flexibility. Thus, the blasts from exploding bombs blew the doors into the shelters or buildings. Even when the doors of air raid shelters were constructed of heavy materials, were mounted on heavy hinges, and were held in closed position by heavy and strong bolts, or other. fastening means of the usual type, when such doors were struck, by blasts from bombs, the doors were found to be onlyas strong as the hardware used in fastening them to the buildings, irrespective of the thickness of the door plate.

According to the present invention, buildings which may function as air raid shelters in time ofwar, are adapted to be formed with walls of substantial construction, such as indicated at Ii, in the drawings.

The structure ll may be constructed of suit able masonry materials, such as reinforced concrete, stone, brick and the like. In the present instance only a portion of a wall of the building is shown, and such wall is depicted as being constructed of reinforced concrete. Since the building as a whole forms no part of the present invention, it has not been deemed necessary-to showmore than the small portion thereof described, because the building may hav any size and configuration desired.

At a suitable point, the structure II or wall of the building, is formed with an entrance opening or passageway having, in plan view, the con figuration shown in Fig. 7.

From the exterior of the structure I I, inwardly for a suitable distance, the entrance opening or passageway is formed with a ceiling l2, 9. floor I3, and side walls It and I5.

At the inner end this outer portion ll of the passageway has mounted therein a rectangular frame It, formed from angle members in well known manner. This frame forms a wall, abutment, or jam it, against which the door is positioned when closed. l

The floor 21 of the main portion of the passageway which is occupied by the door is at a slightly lower level than the level of the floor l3,

- and the portion 21 of the floor may be substantially in the same horizontal plane as the floor oi the building. The structed as nearly flat as is possible, for a purpose to be hereinafter more fully described. I

'Extending laterally from the portion of the frame It adjacent to the wall I5 is a vertically A disposed wall I.

At the end of the wall I9 farthest from the opening H, the structure II has formed therein a vertically disposed arcuate wall 20. The wall 24 extends into the concrete structure II, and the structure U is comparatively thick so that the opening formed therein by the wall will not be injured by bomb explosions.

In order to construct the arcuate wall 20 in the concrete material usedin forming the structure H, a shell 2| may be employed. The shell 2|, formed from sheet metal or the desired gauge or thickness, is shaped to provide the arcuate wall 25, and the vertical edges at each end of the sheet forming the shell 2| are bent to form iianges 22 and 23, respectively.

The bottom of the shell 2| encircles a portion of a circular plate 24 which is set into the floor The top of the shell 2| likewise encircles a portion of a circular plate 25, similar to the plate 24.

hoor 21 should'be conwhen moved from closed to open position and vice versa. the door can be swung through the above referred to angle-o1 approximately 120 degrees.

have a plurality of anchors 28 .(see Figs. 1 and.2)

mounted thereon, which anchors may be embedded in the concrete of the structure H in well known manner so as to retain the shell in position in said structure.

The adjoining edges of the shell 2| and the plates 24 and 25 may be connected by welding, so as to provide a unitary structure.

With the center of the plates 24, 25 as a center and with a radius extending from the center of said plates to the far end of the wall I 8, the opening or entrance 33 is formed with a vertical arcuate side wall 28. The'wali 28 extends from the wall l8 inwardly of the structure U in the manner shown in Fig. 7.

The wall 28 forms one side of a passageway, of which the other side is formed by a wall 29.

The wall 29 extends from the flange 23, inwardly of the structure U for a suitable distance, and terminates in a wall 30 which is arranged substantially in parallel relationship with the wall l5, but which is oifcet with respect to said wall l5 The inner end of the wall 28 terminates at a point distant from the wall 30 an amount approximately equal to the distance between the walls l4, l5, and extending inwardly from the inner end of the wall 28, is a wall 3| which parallels the wall 30.

Between the walls 30 and 3| there is a passageway 32 which extends into the interior of the The center of curvature of the shell 2| and the center of curvature of'the plates 24 and 25 is;,the center 01 the pivotal connection or the door with the structure.

The door is preferably constructed of metal and the door proper consists of'a rectangular. sheet of steel of suiitable thickness, indicated by the reference numeral 36.

The outside periphery of the door on three sides, that is to say, the dimensions of the door are such that the upper edge 31, the outer edge 38, and the bottom edge 29 are spaceda slight distance from the walls 24, 25 and 21, respectively, as shown in Figs. 2, 3 and 8. However, when the door is in closed position, as shown in Figs. 1 and 8, the peripheral edges of said door abut against the Jam or abutment l8, The outer face of the door 35 is formed around the periphery with a finishing strip and the inner face of the door has a similar finishing strip 4| around its periphery (see Figs. 2, 3 and v For the purpose of rotatably supporting the door 35 so thatthe samecan swing about the vertical axis, the portion of the door which is disposed within the circular cavity provided by the arcuate wall 20, is formed in the manner to be hereinafter described.

At the pivotal side or inner vertical edge of the door there are three plates 42, 43 and 44.

opening extending through an arc of approximately one-third the circumference of the shell,

The inner vertical side edge of the door plate 35 is disposed, when the door is in the closed position shown in Fig. 1, at apoint approximateiy midway the breadth of the wall It.

Forming a continuation or the plate 38 and ex-. tending into the circular cavity 45, is the plate The plate 43 is disposed on the outer face of the plates 36 and 42, and extends from the wall I5, when the door is in the closed position shown in Fig. 4, to a point a suitable distance within the cavity 45. A portion of the plate 43 which is disposed within the cavity 45 is bent along a vertical line at an angle away from the outer face of the plate 42, as indicated at 43, Fig. 4.

Likewise, one face of the plate 44 abuts the inner faces of the plates 35 and 42, and said plate 44 extends from a point in alinement with the wall l5, into the cavity 45. The portion of the ptate 44 which is disposed within the cavity 45 is bent along a vertical line so that said plate has a portion 49 disposed at an angle with respect to the plate 42.

The construction is such that the plates 36 and 42 are clamped between a portion of the plates 43 and 44, and the several plates may be united together to form a unitary structure by any suitable means, such as by welding or by means of screws, bolts, or other suitable fastening elements, not shown. I

Pivotally connected to the inner vertical edge of the portion 48 of the plate 43, by means of hinges or similar pivoting elements, 41, is a plate 48.

As shown in Fig. 6, the height of the portion 49 of the plate 44 is somewhat greater than the height of the plate 48.

Extending outwardly from both sides of the plate 42 at points adjacent to the upper and loweredges of the plate 48, are upper and lower horizontally disposed plates 50, 5|, 52 and 53.

- since the trunnions are protected by a a,sso,ee1

Arranged ammo the periphery of the door, is-

The plates u, u, 2 mass constitute horizontalwebs, which in plan are of triangular shape,

' as shown in Fig. 4, and in order to iurther reiniorce the structure and to also retain the end portions of saidplates in position, use is made of a pair of vertically arranged angle members 84 and 55. a

The angle member has a side wall II which lies against the-face oi the plate and a side wall 51 which is arranged" substantiallyat right angles to the side wall SI and extends outward to the portion l! of the plate M.

The angle member ll hasa side wall II which lies against the face oi the plate 42 and a side wall 5! which is arranged substantially at right angles to the side wall I and extends outwardly to the outerangularly disposed edge portions the webs 6i and ll. The angle member Il may be rigidly secured to the plates 42, u, I and I2.-by welding. or by any other suitable means. Theangle -member II should be rigidly seowed to the plates 42, I and i3.

The member 4| is not secured to the edges '01 the plates ll, '53, noris said member secured to the edge of the side wall is ber".

From the ioregoing'it will be sated that the portion of the door which is disposed within the cavity 45 includes splayed' plates, which are ar-- ranged as shown in Figs. 1 and 4 somewhat in the form of a fish tail.

As shown in Fig. 6, the center 01' the bottom plate 24 is formed with an opening Cl, and disposed on theunderside of said plate and having avertical bore 82 arranged in alinement with the opening ii, is a block 63.

The block or member ll constitutes a Journal for a trunnion ll carried by the bottom portion of the door structure, the lower end of" said trun-'- nion being mounted in a thrust bearing 5 disposed in the bore '2. 3

Mounted in'the opening II and surrounding the trunnion N, is a packing OI adaptedto prevent dirt and other foreign matter trom entering'i the bore 62 and the bearing ll mounted therein.

in vertical axial alinement with the opening 6., is

a block 10.

The block or member ll constitutes a journal for a trunnion ll carried by the upper portion of the door structure. The trunnion-H is-detachably connected to thedoor members 42, 49., by means of screws, bolts, or the like 12.

Since the blocks i3 and 10 are embedded in of the angle mema gasket or flexible sealing strip ll.

The sealing strip or gasket ll may be mounted on the flnishing strip 4|, being securely fastened .thereto by means of a binding strip II which may besttached to the periphery oi'the door by means or screws II, as shown in Fig. 3.

The sealing strip'or gasket II is adapted to bear at all times against the surfaces provided'by the walls 21, 34, llz'and 2|, so as to thoroughly seal the joints between the structure II and the door.

In order to provide means tor locking the door in closed position without employing the usual locking bolts, latches. or the like fastening elements, the member. 48, along its vertical outer edge portion ll, is formed with a gasket or flexible the concrete which. forms'the wall structure ll,

said blocks will be. rigidly anchored in'place and the plates 24 and provide means for protecting said blocks from being damaged.

By providing the vertically disposed trunnions the trunnions at a point remote fromthe door opening i1, the likelihood of said trunnions be.- coming damaged as the result of'blastsfrom c:- ploding bombs will be reduced to a minimum, thickened portion of the wall structure IL,

strip 82, as shown best in Figs. 4 and 5.

v The gasket 02 is arranged on the outer face of the member 48, being secured to said member by means oi a binding strip 83 in a manner similar to the manner in which the binding strip I6 retains the gasket 1.! on to the door.

The gasket Ii, as well as the gasket 82, may be constructed oi suitable flexible material, such as rubber composition, or any other material found suitable for use as flexible gaskets. However, the body of the gasket .2 should be somewhat thicker than the body of the gasket I! in order to withstand hard usage and heavy strains.

- The gasket I2 constitutes a pad which is adapted to be moved into engagement with the wall of the-arcuate shell 2| so as to provide means by which rotation of the door on its trunnions 6|,

. this retarded. In other. words, when the memher 0 is disposed in the-position in which the pad 82 engages the walloi the shell 2|, means are provided for braking the rotative movement of the door, irrespective of the position of the door in the passageway.

constituting a part 01' the braking means for retarding the rotation of the door, is a plurality of expansible coil springs, 85.

As shown in Fig. 2, the springs 85 are suitably spaced apart, and as shownin Figs. 4 and 5, said springs are located adjacent to the angle member 58.

.One end of each spring 85 bears against a block 88 carried by the plate 42, and the other end of. each spring bears against the inner face of the member I. The springs 05 normally urge the member 4| away from the stops provided by the horizontal webs II and 53.

In order toposition the plate 48 so that the pad 82 will not engage with the surface of the shell Ii, that is to say, in, Orderto release the braking mean so that the doonwill be free to swing on the pivots provided by the trunnions 64, ii, an

actuator U is provided.

The actuator '1 comprises a rod having a portion thereof formed with screw threads 88, which screw threadedportion is mounted in a ,block ll-securediin the door structure, 42, 49, and-having a bore ll formed with screw threads. at actuator rod 01 is provided with 4 a hand wheel 8|,which hand wheel is located on the inside of the door, so that when the door is in the closed position shown in Fig. l, the hand wheel will be conveniently disposedjfor ready manipulation by an air raid warden or operator, in order toeifectmovement of the actuator so as to applythe braking means, as will be hereinaftermore fully described.

The actuator rod 81 also extends through an elongated opening 92 formed in the member 48 and also formed in a boss 88 on the outer face of said member. 7

At its outer end,.the rod 81 is formed with an enlarged portion or head 84 having an opening 88 formed therein for a purpose to be hereinafter described.

The head 94 of the actuator rod 81' bears against a shoulder or abutment 98 provided by the outer surface of the boss 83 and in doing so retains the member 48 from swinging outwardly as the result of forces exerted by the expansible coil springs 85 against the opposite face of said member, which forces urge the member 48 to swing on the hinges 41 in a direction away from the plate 42.

Mounted on the outer face of the member 48, in a position adjacent to the boss 93, is a bracket 91 having an opening formed therein for receiving the shank of a headed pin or rod 98, as shown bestin Fig. 2.

When the door is not in use, the actuator 81 retains the plate or member 48 in the position shown in Fig. 4, in which position the member 48 lies against the horizontal webs 53. The springs 85 are thus compressed. With the member 48 thus positioned, the pad 82 will be disengaged from the shell 2|, thereby enabling the door to freely rotate on its trunnions except for the slight frictional resistance of the engagement of the gasket with the walls 2|, 28, the ceiling 34, and the floor 27. 7

Assuming that the door is installed at an opening in an air raid shelter and an air raid waming signal has been sounded, the door is placed in the dotted line position shown in Fig. 7, so

that the passageway (I entrance to the air raid shelter is unobstructed. After persons seekshelter in the building, the air raid-warden or other person in charge, moves the door from the open position shown by the dotted lines in Fig. 7 to the closed position shown in Fig. 1. The hand wheel 9|, which is now disposed in a readily accessiblev position at the mouth of the cavity 45, as shown best in Figsml and 5, is turned in the direction in whiohthe headed end 94 of the rod 81 is moved outwardly or away from the boss 93. Since the member 48 is hingedly mounted on the door structure, the springs 85 force said member 48 outwardly in a direction away from the plate 42. The hand wheel 9! should thus be operated so as to permit the springs 85 approximately 90 degrees without breaking the seal of the gasket 18 with the surfaces of the passageway in which the door is disposed.

It will thus be noted that although the braking means provided by the engagement of the pad 82 with the wall of the shell 2| may offer a resistance sufllcient to prevent swinging movements being imparted to the door by ordinary forces, when heavy blasts from bombs or other explosive elements strike the surface of the door exposed to such blasts, the braking means are flexible enough to permit the door to swing on its tru'nnions without damaging or otherwise disrupting the pivotal mounting of the door in the structure if. r t

Due to the manner in which the door is pivotally mounted in the building H, and also due to the arrangement of the hand wheel 9| should the door be swung to a position in which the hand wheel Si is inaccessibly disposed inthe cavity 45, the pin or rod 98 can be removed from the bracket 91 and inserted in the opening 95 of the head 94. The rod 88 can then be used to rotate theactuator rod 81 so as to disengage the pad 82 from the shell 2|, thereby releasing the braking means, so that the door can be readily moved. I r

The construction hereinbefore described provides improved means by which, during bombardments in time of war, the door of an air raid shelter or the like, can be retained in closed positlonunder pressures sufficient for the door to resist average blasts without movement. In the event of close or extremely heavy blasts, the blast pressure on the door will compress the springs 85 sufllciently for the door to move, rather than for the door or its hinges to be damaged. This spring pressure is adapted to brake the inward swing of the door and check such swinging movement within a predetermined arc of safety (compare Fig. 1 with Fig. 7,). After which the spring brake may be released by turning the hand wheel ill, the door moved back to its closed position, and the brake again applied in the manner heretofore described.

In addition to being applicable for installation a in bomb and gas resisting shelters, the improved to move the member 48 a distance suflicient for the pad 82 to bear tightly against the shell 2|. When this operation has been completed the frictional engagement of the elongated pad 82 with the surface of the shell'2l will retain the door firmly in its closed position.

Due to the construction of the door and the manner in which said door is arranged in the passageway, when a blast from a bomb or other explosive element occurs at some place on the exterior of the building, the forces expended by the blast against the exposed surface of the door defined by the outer passageway l1, upon'striking the door may force the door to swing inwardly door herein described issusceptibie for use in other types of buildings and structures, such as in chemical plants, refrigeration and packing plants, fortifications, explosive manufacturing plants, etc In some of its applications the door may be installed in the walls of buildings so as to prevent fumes, gases, or other fluids from readily passing from one room to another room, or from passing from the interior of a building to the exterior thereof.

Having thus described my invention, what I claim is:

1. An air raid shelter comprising a wall having an entrance opening formed therein, a door for closing said entrance opening, saiddoor being arranged within the wall and having pivotal connections mounted in said wall in spaced relation to said entrance opening, means for sealing the joints between the peripheryof said door and the surfaces of said entrance opening, means carried by said door and engageable with said wall for frictionally retarding the swingin movement ofthe door, a plurality of springs acting against said retarding means for urging said retarding means into frictional engagement with said wall, and means for operating said retarding means for retaining said retarding means disengaged from said wall to permit free swinging movement of the door when desired, said retarding means being adapted, when blasts from exploding bombs strike the exposed surface of the door, to permit said door to swing through a limited angle in the entrance opening without opening the seal between the door and the walls of said entrance opening.

2. A building structure of the class described having an entrance opening formed therein, a door jamb formed in said entrance opening, a wall extending laterally from and substantially in alinement with said door jamb, a cavity formed in said structure at the end of said lateral wall farthest from said entrance opening, a door extending across the entrance opening, the lateral wall and the cavity an adapted to abut the door lamb and the lateral wall to close the entrance opening, means disposed in said cavity for pivotally supporting the door in the structure, and means carried by said door and engageable with the wall of said cavity for retarding the swinging movement of said door.

3. A building structure of the class described having an entrance opening formed therein, a door jamb formed in said entrance opening, a wal1 extending laterally from said door jamb, a cavity formed in said structure at the end of said lateral wall farthest from said entrance opening, a door extending across the entrance opening, the lateral wall and the cavity and adapted to abut the door jamb and the lateral wall to close the entrance opening, means disposed in said cavity for pivotally supporting the door in the structure, means carried by said door and engageable with the wall of said cavity for retarding the swinging movement of said door, and mechanism for operating said retarding means for rendering the same inoperative.

4. \A building structure of the class described having an entrance opening formed therein, a door jamb formed in said entrance opening in spaced relation to the outer end thereof, a wall extending laterally from and substantially in alinement with said door jamb, a cavity formed in said structure at the end of said lateral wall farthest from said entrance opening, said cavity having a vertical arcuate wall extending from said lateral wall to a second wall arranged at an angle with respect to said lateral wall, a closure element for closing said entrance opening, said closure element having pivotal connections arranged concentric with the vertical center of said cavity and adapted to lie along the face of said lateral wall and abut sai door jamb when in position to close said entrance opening, and a plate hingedly connected to said closure element and having an edge portion engageable with the wall of said cavity for retarding the swingin movement of said closure element.

5. A building structure of the class described having an entrance opening formed therein, a door jamb formed in said entrance opening in spaced relation to the outer end'thereof, a wall extending laterally from and substantially in alinement with said door jamb, a cavity formed in said structure at the end of said lateral wall farthest from said structure entrance opening, said cavity having a vertical arcuate wall extending from the inner end of said lateral wall, a door for closing said entrance opening, Journals projecting from the bottom and the top of said door and mounted in bearings disposed, respectively,

in the center of curvature of the bottom and the top of said cavity for pivotally supporting said door at a point remote from the entrance opening in the structure, and means disposed within said cavity and pivotally mounted on said door in offset relationship to said .door journals and engageable with the wall of said cavity for retarding the swinging movement of said door.

6. A building structure of the class described having an entrance opening formed therein and including side walls, a top, and a bottom, a door jamb formed in said entrance opening in spaced relation to the outer end thereof and including a top higher than the top of the entrance opening, a bottom lower than the bottom of the entrance opening, and laterally extending walls, one lateral wall having a width greater than the width of the other lateral wall, a cavity formed in said structure at the end of the lateral wall of greatest width, a door for closing said entrance opening, means disposed in said cavity for pivotally supporting the door in said structure, said pivot means being located in spaced relation to an edge of said door in said cavity, and means disposed within said cavity and pivotally mounted on said door in offset relationship to said door pivot means and engageable with the wall of said cavity for retarding the swinging movement of said door.

7. A building structure of the class described having an entrance opening formed therein, a door jamb formed in said entrance opening in spaced relation to the outer end thereof, a wall extending laterally from and substantially in alinement with said door jamb, a cavity formed in said structure at the end of said lateral wall farthest from said entrance opening, a door extending across the entrance opening. the lateral wall and the cavity arid adapted to abut the door jamb and the lateral wall to close the entrance opening, means disposed in said cavity for pivotally supporting the door in the structure, and a plate hingedly connected to said door and having an edge portion adapted to engage the wall of said cavity for retarding the swinging movement of said door.

8. In a structure of the class described, a wall having an entrance passageway formed therein, a cylindrical cavity formed vertically in said wall in spaced relation and offset with respect to said passageway, a ledge formed in said structure between the passageway and said cavity, a closure element for closing said entrance passageway, said closure element having pivotal connections with said wall arranged concentric with the vertical center of said cavity, said ledge limiting the swinging movement of said closure element in one direction, and a plate pivotally carried by said closure element and movable independently with respect to said closure element and having a portion engageable with the wall of said cavity for retarding the swinging movement of said closure element.

' PALMER BESCHERER. 

